Apologies for exhuming an apparently closed topic, but the Glynor post doesn't seem to apply in my case.
I'm using the 1513+, 5 bay/ 4Tb Drives, Raid redundant array. The Diskstation monitor shows all drives are in good health, and there is lots of available space. My Library is stored on the C Drive, virtually all music is on the Diskstation. I use a root music folder, a series of date specific subfolders and below them the sub/sub folders that actually hold the files. (I use dated folders for rips or d/ls within a given time period.)
Starting 3-4 months ago, I began noticing that files had disappeared from the Synology. At first, this seemed limited to a specific time period. Now, it appears much more random, although by and large the problem is worst with d/ls or rips starting in approximately May of this year. When I go to the dated subfolder in question through Explorer, I can find the subfolder where the files should be, and a number of sub/sub folders with files within them remain in place, but there's no trace of the missing files or the folders in which they were originally located. I've even used the start/search process to see if they're located elsewhere, but come up empty. I back up my library after each day of usage
I did set up recycle folder for my Music folder, as was previously suggested in the Synology forum. (I have 4 root folders - music; photos; video; and shared (or miscellaneous). There's no sign of them there. As noted, all music is stored in sub/subfolders within the Music root folder.
I'm scrambling to recover lost files by redownloading them where I can, but I'd like to know how to halt the process and if possible restore the files that I've lost. I'd appreciate any help that users or staff can provide. Let me know if more information would b e helpful.